/*******************************************************************************
 * Software Name : RCS IMS Stack
 *
 * Copyright (C) 2010 France Telecom S.A.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 ******************************************************************************/

package com.gsma.rcs.utils;

import java.util.Vector;

/**
 * FIFO buffer
 * 
 * @author JM. Auffret
 */
public class FifoBuffer {
    /**
     * Number of objects in the buffer
     */
    private int nbObjects = 0;

    /**
     * Buffer of objects
     */
    private Vector<Object> fifo = new Vector<Object>();

    /**
     * Add an object in the buffer
     * 
     * @param obj Message
     */
    public synchronized void addObject(Object obj) {
        fifo.addElement(obj);
        nbObjects++;
        notifyAll();
    }

    /**
     * Read an object in the buffer. This is a blocking method until an object is read.
     * 
     * @return Object
     */
    public synchronized Object getObject() {
        Object obj = null;
        if (nbObjects == 0) {
            try {
                wait();
            } catch (InterruptedException e) {
                // Nothing to do
            }
        }
        if (nbObjects != 0) {
            obj = fifo.elementAt(0);
            fifo.removeElementAt(0);
            nbObjects--;
            notifyAll();
        }
        return obj;
    }

    /**
     * Read an object in the buffer. This is a blocking method until a timeout occurs or an object
     * is read.
     * 
     * @param timeout Timeout
     * @return Message
     */
    public synchronized Object getObject(int timeout) {
        Object obj = null;
        if (nbObjects == 0) {
            try {
                wait(timeout);
            } catch (InterruptedException e) {
                // Nothing to do
            }
        }
        if (nbObjects != 0) {
            obj = fifo.elementAt(0);
            fifo.removeElementAt(0);
            nbObjects--;
            notifyAll();
        }
        return obj;
    }

    /**
     * Close the buffer
     */
    public synchronized void close() {
        // Free the semaphore
        this.notifyAll();
    }

    /**
     * Get FIFO size
     * 
     * @return size of the FIFO
     */
    public int size() {
        return fifo.size();
    }

    /**
     * clean FIFO
     * 
     * @return size of the FIFO
     */
    public void clean(int size) {
        if (fifo.size() > size) {
            while (size > 0) {
                fifo.removeElementAt(0);
                nbObjects--;
                size--;
            }
        }
    }
}
